The purposes of this study are to assess the feasibility of continuous long term infusion of iododeoxyuridine (IdUrd) and accelerated hyperfractionated radiotherapy (XRT) in the management of high grade gliomas; to determine local and systemic toxicities of this regimen; to investigate serum levels of IdUrd; to determine the maximum tolerated dose of IdUrd; and to assess the incorporation of IdUrd in tumor and proliferating target cell.